Simplify the following expression: $k = \dfrac{x + 4}{5x + 6} \div \dfrac{1}{3}$
Explanation: Dividing by a number is the same as multiplying by its inverse. $k = \dfrac{x + 4}{5x + 6} \times \dfrac{3}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $k = \dfrac{(x + 4) \times 3} {(5x + 6) \times 1}$ $k = \dfrac{3x + 12}{5x + 6}$